JP2014059246A - Radiation detector and method for manufacturing the same - Google Patents

Abstract

An object of the present invention is to improve the bonding quality of a radiation detector having a structure in which a moisture-proof body is bonded to an array substrate.
A radiation detector includes a photoelectric conversion element two-dimensionally arranged in an effective pixel region on a glass substrate, a tab pad outside the effective pixel region, a plurality of wirings 29 extending to the tab pad, and protection for protecting the wirings. An array substrate provided with a film, a scintillator layer that covers the effective pixel area of the array substrate and converts radiation into fluorescence, and a metal molded body that covers the scintillator layer and faces a portion surrounding the scintillator layer of the array substrate A moisture-proof body having an adhesive surface; and an ultraviolet curable adhesive layer that is interposed between the adhesive surface and the array substrate and adheres the adhesive surface to the array substrate. The ratio of the width of the wiring 29 in the portion covered with the adhesive layer to the width between the adjacent wirings 29 is 1 or less.
[Selection] Figure 10

Description

  Embodiments generally relate to radiation detectors and methods of manufacturing the same.

  A planar X-ray detector using an active matrix has been developed as a new generation X-ray diagnostic detector. This X-ray detector detects the irradiated X-rays and outputs an X-ray image or a real-time X-ray image as a digital signal. In this X-ray detector, X-rays are converted into visible light, that is, fluorescence by a scintillator layer, and this fluorescence is converted into signal charges by a photoelectric conversion element such as an amorphous silicon (a-Si) photodiode or CCD (Charge Coupled Device). By acquiring the image.

As a material of the scintillator layer, cesium iodide (CsI): sodium (Na), cesium iodide (CsI): thallium (Tl), sodium iodide (NaI), or gadolinium oxysulfide (Gd ₂ O ₂₎ S) or the like is used. The scintillator layer can improve resolution characteristics by forming grooves by dicing or the like, or by depositing by a vapor deposition method so that a columnar structure is formed. There are various scintillator materials as described above, and they are properly used depending on the application and necessary characteristics.

  In order to improve the use efficiency of fluorescence and improve sensitivity characteristics, a reflective film may be formed on the scintillator layer. In this case, of the fluorescence emitted from the scintillator layer, the fluorescence directed to the opposite side with respect to the photoelectric conversion element side is reflected by the reflection film, and the fluorescence reaching the photoelectric conversion element side is increased.

  The reflective film is formed by coating a metal layer with high fluorescence reflectance such as silver alloy or aluminum on the scintillator layer, or by applying a light-scattering reflective film made of a light-scattering substance such as TiO2 and a binder resin. It is formed by the method to do. In addition, a method of reflecting scintillator light by bringing a reflecting plate having a metal surface such as aluminum into close contact with the scintillator layer instead of forming a reflective film on the scintillator layer has been put into practical use.

  A moisture-proof structure for protecting a scintillator layer, a reflection film, a reflection plate, and the like from an external atmosphere to suppress deterioration of characteristics due to moisture and the like is an important component for making a detector a practical product. In particular, when a CsI: Tl film or a CsI: Na film, which is a material that is greatly deteriorated by moisture, is used as a scintillator layer, high moisture-proof performance is required. As a moisture-proof structure, for example, a moisture-proof layer such as aluminum foil is adhered and sealed to the substrate at the periphery to maintain moisture-proof performance, or a moisture-proof layer such as aluminum foil or thin plate and the substrate are connected via a surrounding ring-shaped structure. There are structures that are adhesively sealed.

JP 2009-128023 A JP-A-5-242841

  However, when ultraviolet rays are irradiated from the back of the array substrate and the hat-shaped moisture-proof layer is adhesively sealed with an ultraviolet curable adhesive, the ultraviolet rays are blocked by the metal wiring of the array substrate lead-out portion, so the adhesive curing reaction Does not proceed, and there is a possibility of causing deterioration in moisture-proof reliability due to poor adhesion and reduced adhesive strength.

  In view of this, an object of the embodiment is to improve the bonding quality of a radiation detector having a structure in which a moisture-proof body is bonded to an array substrate.

  In order to achieve the above object, a radiation detector according to an embodiment includes an ultraviolet transmissive substrate, photoelectric conversion elements that are two-dimensionally arranged in an effective pixel region on the substrate, and a tab pad outside the effective pixel region. An array substrate provided with a plurality of wirings extending from the effective pixel region to the tab pad, and a protective film for protecting the wirings; a scintillator layer that covers the effective pixel region of the array substrate and converts radiation into fluorescence; A moisture-proof body comprising a metal molded body covering the scintillator layer and having an adhesive surface facing a portion surrounding the scintillator layer of the array substrate, and interposed between the adhesive surface and the array substrate. An adhesive surface and an ultraviolet curable adhesive layer for adhering the array substrate, and between the adjacent wirings having a width of the wiring at a portion covered with the adhesive layer Ratio is equal to or is 1 or less with respect to.

  In addition, the method of manufacturing the radiation detector according to the embodiment includes a photoelectric conversion element that is two-dimensionally arranged in an effective pixel region on a UV transmissive substrate, a tab pad outside the effective pixel region, and the effective pixel region. An array substrate forming step of forming an array substrate by providing a plurality of wires extending to the tab pad and a protective film for protecting the wires, and forming a scintillator layer that covers the effective pixel region of the array substrate and converts radiation into fluorescence A scintillator layer forming step, a metal molded body covering the scintillator layer, and forming a moistureproof body having an adhesive surface facing a portion surrounding the scintillator layer of the array substrate, and the bonding An adhesive application step of applying an ultraviolet curable adhesive to the surface; and after the adhesive application step, the adhesive surface is attached to the array substrate in a reduced-pressure atmosphere. An adhesive step of irradiating the array substrate with ultraviolet rays from a surface opposite to the adhesive of the array substrate, and having the width of the wiring adjacent to the portion covered with the adhesive layer The ratio with respect to the width between them is 1 or less.

It is a typical perspective view of the radiation detection device by one embodiment. It is a circuit diagram of the radiation detector by one Embodiment. It is a block diagram of the radiation detection apparatus by one Embodiment. It is a partially expanded sectional view of the radiation detector by one Embodiment. It is a top view of the radiation detector by one Embodiment. It is a side view of the radiation detector by one Embodiment. It is a top view of an array substrate according to an embodiment. It is an expanded sectional view near a collar part of a moisture-proof body by one embodiment. It is the IX-IX arrow partial expanded sectional view of FIG. It is a top view which shows the wiring space | interval of the array substrate by one Embodiment. It is a top view which shows the wiring space | interval of the array board | substrate by another example.

  Hereinafter, a radiation detector according to an embodiment will be described with reference to the drawings. In addition, the same code | symbol is attached | subjected to the same or similar structure, and the overlapping description is abbreviate | omitted. This embodiment is merely an example, and the present invention is not limited to this.

  FIG. 1 is a schematic perspective view of a radiation detection apparatus according to an embodiment.

  The radiation detector 11 of this embodiment is an X-ray plane sensor that detects an X-ray image that is a radiation image, and is used for general medical applications, for example. The radiation detection apparatus 10 includes the radiation detector 11, a support plate 31, a circuit board 30, and a flexible board 32. The radiation detector 11 has an array substrate 12 and a scintillator layer 13. The radiation detector 11 detects incident X-rays and converts them into fluorescence, and converts the fluorescence into electrical signals. The radiation detection apparatus 10 drives the radiation detector 11 and outputs an electrical signal output from the radiation detector 11 as image information. The image information output by the radiation detection apparatus 10 is displayed on an external display or the like.

  The array substrate 12 has a glass substrate 16. A plurality of fine pixels 20 are arranged in a square lattice pattern on the surface of the glass substrate 16. Each pixel 20 includes a thin film transistor 22 and a photodiode 21. On the surface of the glass substrate 16, the same number of gate lines 18 as the square lattice rows in which the pixels 20 are arranged extend between the pixels 20. Further, the same number of data lines 19 as the number of square lattice columns in which the pixels 20 are arranged extend between the pixels 20 on the surface of the glass substrate 16. The scintillator layer 13 is formed on the surface of the effective pixel region where the pixels 20 of the array substrate 12 are arranged.

  The scintillator layer 13 is provided on the surface of the array substrate 12 and generates fluorescence in the visible light region when X-rays enter. The generated fluorescence reaches the surface of the array substrate 12.

The scintillator layer 13 is formed by forming, for example, cesium iodide (CsI): thallium (Tl) or sodium iodide (NaI): thallium (Tl) into a columnar structure by a vacuum deposition method. The thickness of the pillar (pillar) of the columnar structure crystal of CsI: Tl is, for example, about 8 to 12 μm at the outermost surface. The thickness of the scintillator layer 13 is about 600 μm, for example. Alternatively, gadolinium oxysulfide (Gd ₂ O ₂ S) phosphor particles are mixed with a binder material, applied onto the array substrate 12, fired and cured, and formed into a square column by forming grooves by dicing with a dicer. Then, the scintillator layer 13 may be formed. Between these columns, air or an inert gas such as nitrogen (N ₂ ) for preventing oxidation may be enclosed, or a vacuum state may be provided.

  The array substrate 12 receives the fluorescence generated in the scintillator layer 13 and generates an electrical signal. As a result, the visible light image generated in the scintillator layer 13 by the incident X-ray is converted into image information expressed by an electrical signal.

  The radiation detector 11 is supported by the support plate 31 so that the surface opposite to the surface on which the scintillator layer 13 is formed and the support plate 31 are in contact with each other. The circuit board 30 is disposed on the opposite side of the support plate 31 with respect to the radiation detector 11. The radiation detector 11 and the circuit board 30 are electrically connected by a flexible board 32.

  FIG. 2 is a circuit diagram of the radiation detector according to the present embodiment.

  Each photodiode 21 is connected to the gate line 18 and the data line 19 through a thin film transistor 22 which is a switching element. In addition, a storage capacitor 27 is connected to each photodiode 21 in parallel. The storage capacitor 27 may also serve as the capacitance of the photodiode 21 and is not always necessary.

  The photodiode 21 and the storage capacitor 27 connected in parallel to the photodiode 21 are connected to the data line 19 via the thin film transistor 22. A gate electrode of the thin film transistor 22 is connected to the gate line 18.

  The thin film transistors 22 of the pixels 20 located in the same row of the array are connected to the same gate line 18. The thin film transistors 22 of the pixels 20 located in the same column of the array are connected to the same data line 19.

  Each thin film transistor 22 has a switching function for accumulating and discharging charges generated by the incidence of fluorescence on the photodiode 21. The thin film transistor 22 is at least partially composed of a semiconductor material such as amorphous silicon (a-Si) as an amorphous semiconductor, which is a crystalline semiconductor material, or polysilicon (P-Si), which is a polycrystalline semiconductor. Has been.

  In FIGS. 1 and 2, the pixels are described only for 5 rows and 5 columns or 4 rows and 4 columns, but actually, more pixels are formed according to the resolution and the imaging area.

  FIG. 3 is a block diagram of the radiation detection apparatus according to the present embodiment.

  The radiation detection apparatus 10 includes a radiation detector 11, a gate driver 39, a row selection circuit 35, an integration amplifier 33, an A / D converter 34, a parallel / serial converter 38, and an image synthesis circuit 36. Have. The gate driver 39 is connected to each gate line 18 of the radiation detector 11. The gate driver 39 controls the operation state of each thin film transistor 22, that is, on and off. The integrating amplifier 33 is connected to each data line 19 of the radiation detector 11.

  The row selection circuit 35 is connected to the gate driver 39. The parallel / serial converter 38 is connected to the integrating amplifier 33. The A / D converter 34 is connected to a parallel / serial converter 38. The A / D converter 34 is connected to the image composition circuit 36.

  The integrating amplifier 33 is provided on a flexible substrate 32 that connects the radiation detector 11 and the circuit board 30, for example. The other elements are provided on the circuit board 30, for example.

  The gate driver 39 receives the signal from the row selection circuit 35 and sequentially changes the voltage of the gate line 18. The row selection circuit 35 sends a signal for selecting a predetermined row for scanning the X-ray image to the gate driver 39. The integrating amplifier 33 amplifies and outputs a very small charge signal output from the radiation detector 11 through the data line 19.

  FIG. 4 is a partially enlarged sectional view of the radiation detector according to the present embodiment.

  On the surface of the array substrate 12, an insulating protective film 28 that covers detection elements such as photodiodes 21 and thin film transistors 22, and metal wirings such as gate lines 18 (see FIG. 1) and data lines 19 (see FIG. 1). Is formed. The scintillator layer 13 is formed on the surface of the protective film 28 so as to cover the effective pixel region in which the pixels 20 are arranged.

  A reflection film 14 is provided on the surface of the scintillator layer 13. The reflection film 14 reflects the fluorescent light generated in the scintillator layer 13 that moves away from the array substrate 12 to the array substrate 12 side. As a result, the amount of fluorescence reaching the photodiode 21 increases.

The reflective film 14 is formed by a method of forming a metal having a high fluorescence reflectance such as a silver alloy or aluminum on the scintillator layer 13. Alternatively, a reflector having a metal surface such as aluminum adhered to the scintillator layer 13 or a diffuse reflective film 14 made of a light scattering material such as TiO ₂ and a binder resin may be applied and formed. Note that the reflective film 14 is not necessarily required due to characteristics such as resolution and luminance required for the radiation detector 11.

  The radiation detector 11 is provided with a moisture-proof body 15 so as to surround the scintillator layer 13 and the reflective film 14.

  FIG. 5 is a top view of the radiation detector according to the present embodiment. FIG. 6 is a side view of the radiation detector according to the present embodiment. FIG. 7 is a top view of the array substrate according to the present embodiment. In FIG. 7, details inside the effective pixel region and illustration of the protective film 28 are omitted.

  The moisture-proof body 15 is formed in a hat shape with a raised central portion. The peripheral portion of the moisture-proof body 15 is a flat belt-like collar portion 50. The flange 50 is formed in a band shape surrounding the outside of the effective pixel region 60 where the scintillator layer 13 on the surface of the array substrate 12 is formed. A flat top plate portion 51 is formed inside the flange portion 50. A slope portion 52 is formed between the flange portion 50 and the top plate portion 51.

  The flange 50 faces the array substrate 12. The flange 50 and the array substrate 12 are bonded. The scintillator layer 13 (see FIG. 4) and the reflective film 14 (see FIG. 4) formed on the array substrate 12 are covered with the top plate portion 51 and the slope portion 52 of the moisture-proof body 15. The moisture-proof body 15 protects the scintillator layer 13 and the reflective film 14 from the outside air and humidity, and suppresses deterioration of characteristics.

  The moisture-proof body 15 is made of, for example, an aluminum alloy foil having a thickness of 0.1 mm. The moisture-proof body 15 is formed of an aluminum alloy foil such as A1N30-O material or an aluminum foil. The width | variety of the collar part 50 is 5 mm, for example. The material of the moisture-proof body 15 is not limited to Al or Al alloy, and other metal materials may be used. However, in the case of Al or Al alloy foil material, since the X-ray absorption coefficient is small as a metal material, the X-ray absorption loss in the moisture-proof body 15 can be suppressed, and the merit is great, and it is processed into a hat shape. Even in the case, it is excellent in workability.

  The array substrate 12 is provided with a tab pad 26 in which the end of each of the gate line 18 (see FIG. 1) and the data line 19 (see FIG. 1) and other terminals are exposed. A wiring 29 such as a gate line 18 and a data line 19 extending from the effective pixel region is connected to the tab pad 26. The wiring 29 is made of a low resistance metal material such as Al. The tab pad 26 is arranged along the side of the array substrate 12. The tab pad 26 connected to the gate line 18 and the tab pad 26 connected to the data line 19 are arranged along different sides.

  These tab pads 26 are TAB-connected to the flexible substrate 32 (see FIG. 1) using an anisotropic conductive film (ACF). As a result, the array substrate 12 is electrically connected to the circuit substrate 30 (see FIG. 1).

  FIG. 8 is an enlarged cross-sectional view of the vicinity of the collar portion of the moisture-proof body according to the present embodiment. FIG. 9 is a partial enlarged cross-sectional view taken along the line IX-IX in FIG.

  An adhesive layer 40 is interposed between the flange portion 50 of the moisture-proof body 15 and the array substrate 12. The adhesive layer 40 is provided in a band shape that surrounds the outside of the region where the scintillator layer 13 is formed on the surface of the array substrate 12 along the flange 50. Accordingly, at least a part of the flange portion 50 is connected to the wiring 29 extending from the gate line 18 (see FIG. 1) or the data line 19 (see FIG. 1) to the tab wiring 26 provided on the outer periphery of the array substrate 12. It is opposed to sandwich the protective film 28 and the adhesive layer 40. The adhesive layer 40 is formed of an ultraviolet curable epoxy adhesive.

  When adhering the moisture-proof body 15 to the array substrate 12, an adhesive is applied to the collar portion 50 of the moisture-proof body 15 by a dispenser, and then the predetermined number of the array substrate 12 on which the scintillator layer 13 and the reflective film 14 are formed in a reduced-pressure atmosphere. Crimp to the position. By adhering the moisture-proof body 15 to the array substrate 12 in a reduced-pressure atmosphere, a moisture-proof structure having excellent mechanical strength under reduced pressure assuming airplane transportation can be formed.

  Thereafter, ultraviolet rays 70 are irradiated from the back side of the array substrate 12, that is, the side of the glass substrate 16 opposite to the side where the pixels 20 are formed. The ultraviolet light 70 passes through the glass substrate 16 and the protective film 28 and reaches the adhesive. When the ultraviolet rays reach the adhesive through the space of the lead-out wiring part, the polymerization reaction of the adhesive starts and the cross-linking reaction proceeds to cure the adhesive. As a result, the adhesive layer 40 that bonds the moisture-proof body 15 and the array substrate 12 is formed.

  When the ultraviolet rays are irradiated from the back side of the array substrate 12, the metal wiring 29 in the lead-out wiring portion blocks the ultraviolet rays. For this reason, it is necessary to secure a space (inter-wiring width) for transmitting ultraviolet rays in the lead-out wiring portion. Therefore, according to the present embodiment, the metal wiring 29 in the lead-out wiring portion is designed so that the line (wiring width) / space (inter-wiring width) is 1.0 or less.

  FIG. 10 is a top view showing wiring intervals of the array substrate according to the present embodiment.

  Since the metal wiring in the lead-out wiring portion is gathered according to the pitch of the tab pad 26, diagonal wiring is required, and the space (inter-wiring width) tends to be narrowed. In the example of FIG. 10, since the angle of the oblique wiring is gentle, line (L) / space (S) = 40 μm / 80 μm = 0.5, and a sufficient space for transmitting ultraviolet rays is secured. Note that the pitch (distance between the centers of adjacent wirings 29) at this time is 120 μm.

  FIG. 11 is a top view showing the wiring interval of the array substrate according to another example of the present embodiment.

  This example is a case of a narrow frame structure in which the effective pixel region 60 is wide, and a steep diagonal wiring is formed in the lead-out wiring portion. When such a steep diagonal wiring is used, for example, when the pitch is 65 μm, and the wiring width is 40 μm, the space between the wirings 29 is 25 μm, and the line / space = 40/25 = 1.6, There is not enough space for UV transmission. Therefore, in this example, the wiring width is narrowed to 25 μm, and the inter-wiring width (space) is narrowed to 40 μm, and line / space = 0.625.

  As in these examples, by setting the line / space to 1 or less, it is possible to ensure a sufficient space for UV transmission. As a result, a cross-linking reaction also occurs in the adhesive that is shaded by the wiring 29 and is not directly irradiated with ultraviolet rays, and is cured.

As described above, in this embodiment, in the structure in which the lead-out wiring portion of the array substrate 12 and the flange portion 50 of the hat-shaped moisture-proof body 15 are bonded and sealed with the ultraviolet curable adhesive, the line (wiring width) of the array substrate lead-out wiring portion is used. ) / Space (inter-wiring width) is set to 1.0 or less to secure an ultraviolet transmitting space. Ultraviolet rays can reach the bonding portion from the back side of the array substrate 12 through the space between the wirings 29, and the moisture-proof body 15 can be sealed with a high bonding force. Therefore, the adhesion quality of the moisture-proof body 15 can be improved, and a highly reliable moisture-proof structure that is stable in strength can be provided.
[Other embodiments]

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

DESCRIPTION OF SYMBOLS 10 ... Radiation detection apparatus, 11 ... Radiation detector, 12 ... Array substrate, 13 ... Scintillator layer, 14 ... Reflection film, 15 ... Moisture-proof body, 16 ... Glass substrate, 18 ... Gate line, 19 ... Data line, 20 ... Pixel , 21 ... Photodiode, 22 ... Thin film transistor, 26 ... Tab pad, 27 ... Storage capacitor, 28 ... Protective film, 29 ... Wiring, 30 ... Circuit board, 31 ... Support plate, 32 ... Flexible board, 33 ... Integration amplifier, 34 ... A / D converter, 35 ... row selection circuit, 36 ... image composition circuit, 38 ... parallel / serial converter, 39 ... gate driver, 40 ... adhesive layer, 50 ... collar, 51 ... top plate, 52 ... Slope portion, 60 ... effective pixel region, 70 ... UV

Claims (3)

An ultraviolet transmissive substrate, photoelectric conversion elements two-dimensionally arranged in an effective pixel region on the substrate, a tab pad outside the effective pixel region, a plurality of wirings extending from the effective pixel region to the tab pad, and An array substrate provided with a protective film for protecting the wiring;
A scintillator layer for covering the region where the photoelectric conversion elements of the array substrate are arranged and converting radiation into fluorescence;
A moisture-proof body comprising a metal molded body covering the scintillator layer and having an adhesive surface facing a portion surrounding the scintillator layer of the array substrate;
An ultraviolet-curing adhesive layer that is interposed between the adhesive surface and the array substrate to bond the adhesive surface and the array substrate;
Comprising
The radiation detector, wherein a ratio of a width of the wiring in a portion covered with the adhesive layer to a width between adjacent wirings is 1 or less.   The radiation detector according to claim 1, wherein the wiring is made of a metal that does not transmit ultraviolet rays. A photoelectric conversion element that is two-dimensionally arranged in an effective pixel region, a tab pad outside the effective pixel region, a plurality of wirings extending from the effective pixel region to the tab pad, and the wirings are protected on an ultraviolet transmissive substrate. An array substrate forming step of forming an array substrate by providing a protective film;
A scintillator layer forming step of forming a scintillator layer that covers the region where the photoelectric conversion elements of the array substrate are arranged and converts radiation into fluorescence;
A moisture-proof body forming step of forming a moisture-proof body having a bonding surface facing a portion surrounding the scintillator layer of the array substrate, which is a metal molded body covering the scintillator layer;
An adhesive application step of applying an ultraviolet curable adhesive to the adhesive surface;
After the adhesive application step, an adhesive step of pressing the adhesive surface against the array substrate under a reduced pressure atmosphere and irradiating ultraviolet rays from the surface opposite to the adhesive of the array substrate;
Comprising
The method of manufacturing a radiation detector, wherein a ratio of a width of the wiring in a portion covered with the adhesive layer to a width between adjacent wirings is 1 or less.

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